Thermic circuit-closer for electromagnetic apparatus.



G. WHITE. THERMIG CIRCUIT CLOSER FOR ELECTROMAGNETIC APPARATM. 972,964.

APPLICATION FILED SEPT. 2, 1909.

Patented 90b. 18, 1910.

T0 BELL 2 I fZJ enwr: JW

j 70 BELL UNITED STATES- PATENT, OFFICE.

GARRETT WHITE, OF CHAPEL HILL, TENNESSEE, ASSIGNOR OF ONE-HALF T0 WILLIAM B. NEELY, OI CHAPEL HILL, TENNESSEE.

Specification of Letters Patent.

Patented oec. is, 1910,

Application filed September 2, 1909. Serial lto. 515,987.

To all whom it may concern:

Be it known that I, GARRETT WHITE, a citizen of the United States of America, and a resident of Chapel Hill, Marshall county, in the State of Tennessee, have invented a new and useful Improvement in Thermic Circuit-Closers for Electromagnetic Apparatus, of which the following is a specification.

This invention relates to those circuit closers of electromagnetic temperature alarms and other electromagnetic apparatus in which a bell circuit for example is automatically closed by a column of mercury when the heat rises to a predetermined degree.

The leading objects of the present invention are to prevent humidity or dampness within the bore of an open-topped glass tube for the mercury, in such a circuit closer; and,'at the same time, to simplify the construction of the device and reduce the, cost of manufacture. The first of these fobjects is accomplished by providin an open-topped glass tube of. suflicient 1ameter with a lining, molded in situ, of a material non-absorbent to mercury but absorbent of dam ness.

Other ob ects will be set forth. in the gen eral description which follows.

The accompanying drawing is a sectional face view of the lmproved circuit closer.

A suitableupright support, I, which isprefera y the customary wooden backboard is provided with th'ree binding osts, H, H, H and beneath the central binding post H, an-open-ended glass tube, G, G, G", is attached by metallic bridge pieces or staples, F, F The glass tube G G G2 is made of large tubing, as compared with those heretofore in use; its main body portion (G) includin its upper end, and its lower end portion are or may be of one and the same diameteu and in line with each other, and between them there is a single expansion (G) to form the mercury chamber. Within said body portion G of the glass tube, a lining, E, of plaster of paris is molded in situ around a central wire of suitable gage which is Withdrawn when the plaster is nearly hardened. Provision is thus made for inclosing the movable wire or needle; 0:, and the mercury column, 6, within a bore, 0, the walls of which are wholl of material which tends to prevent humidity within the bore, by absorbing dampness, said material being absorbent of dampness and non-ab-,

sorbent to mercury, and at the same time a bore that is readily fitted with accuracy to the needle a.

The expansion G is supplied in custom- The other extremity of the wire C is electrically connected to the bindin post H.

The needle a, inserted into tile upper end of the glass tube, is fastened at any desired 'depthby the binding post H, which is connected by a wire B to the binding post H,

A scale, A, on the upper portion of the backboard I, in juxtaposition to the extremity a of the needle (1, may conveniently indicate the degree of heat for which the circuit closer is set.

To set the device for operation at a given temperature, the needle a is loosened in the binding post H, and is then set at an desired degree in warm air or water wit the aid of an accurate thermometer, after which the needle is fastened in the binding post. After hanging the backboard I in'a suitable position, the terminal wires 1 and 2 of a bell circuit or other electric circuit are fastened in the binding posts H and H respectively.

.Having thus described said improvement, I claim as my invention and desire to patent under this specification:

1. A thermic circuit closer for an electric circuit having, in combination, an opentopped glass tube constructed with a mercury-chamber expansion near its lower end, a lining of a material absorbent of dam ness and non-absorbent to mercurywithin the main body of said tube includin its upper end, a lower'contact Wire seale within the lower end of the tube, and an endwise movable needle extending into the upper end.

of said lined tube; said expansion and the lower end of the' lined portion of the tube being occupied by mercury.

2. A thermic circuit closer for an electric circuit, having, an open-topped glass tube supported in upright position and constructed with a cylindrical main portion including its upper end, a relatively short subjacent cy-- lindrical portion including its lower end and I 5 a mercury chamber expansion Connecting said cylindrical portio s and supplied with mercury, 21 lining of p aster of paris Within said main portion, a filling of plaster of paris Within said subjacent portion, a. mov- 10 able needle extending downward a variable distance Within the upper end of said lined emeee tube to contact with the mercury column,- and a lower contact wire sealed Within the lower end of the tube by said filling, said lining being adapted to prevent humidity 15 Within the tube by absorbing dampness, substsntially as hereinbefore specified.

v GARRETT WHITE.

' Witnesses:

J. B. HAsTINGs, R. O. BELL. 

